Have you had any imaging, or Drs assessment of your back pain?
If so what was the cause or diagnosis?
What levels are affected?

I'm thinking the massager was too strong, or used to vigorously, and worsened /irritated the areas of the spine/muscles that is the problem spot.

muscle spasms can seem like a heart issue - but it is always good to have it checked out - just so you know if it is or isn't.